Parallels Plesk Automation (PPA) service node failed down because of third-party reasons. As an example: hardware failure, operating system crash or any another reason standing out of Parallels responsibility.
How can it be restored?
Parallels Plesk Automation (PPA) does not have utility for restoration data from crashed Service Node. But Feature Request for implemention of such functionality is created, it will be implemented in the future updates, Feature Request ID #1889740.
While we strongly recommend you to have third-party backup/restore solution which provide ability to create a server-wide backup.